advanced photo system (APS)
The Advanced Photo System(APS) is a 35mm film format for traditional photography. The film size corresponds to the classic 24 mm wide film, which is housed in a compact film cassette. Externally, the film cassette is distinguished only by markings on the top of the cassette. The actual bidl format is slightly smaller and is 30.2 x 16.7 mm.
The photo format, developed by several Japanese companies in the mid-1990s, works with films that have an additional magnetic layer on top for storing additional information. The characteristic values of the photo such as the film speed, the date, the exposure data, the image format and additional texts are stored on this layer and can be read out after film development and printed in the photo.
In the APS system, the film remains in the compact film cassette after development, which also allows for later post-processing.
The APS system recognizes three image formats, the High Definition (APS-H) with an aspect ratio of 16:9, the Panorama format (APS-P) with an aspect ratio of 3:1 and the Classic format (APS-C) with 3:2. However, exposure is always in the High Definition format; the other image formats are obtained during processing. The APS-C format has a size of 23 mm x 15 mm and is also used for image sensors.
Since image sensors usually have a smaller format than the 35 mm format of APS films, the captured image is cropped to fit the size of the image sensor. This cropping is done with the so-called crop factor. For the APS-C format with a size of 25.1 mm x 16.7 mm, the crop factor is 1.5, which means that the captured image is reduced in size by a factor of 1.5.